I always believed in my abilities as a writer, but the disparity between what I write and what is made in Hollywood is HUGE. This is very likely why I daily fight to push my scripts forward.
Write what you think is good, refine it, send it out, and repeat for many years. Find a day job that is satisfying, and also lets your mind wander so that the only pressure you feel is to become a better writer, not 'get rich in Hollywood'.